Not to multiple enemies, he can't.
To be frank, if at epic tier you're fighting an Astral Kraken or a Balor, multiple enemies is irrelevant because those targets are so important you *need* them dead *now*. Not later, *now* because the more time you give them the more damage you're going to suffer (terrible terrible damage to borrow a starcraft term). If you have a Barbarian in your party with Hurricane of Blades vs. an Astral Kraken, *one* mistake you can have a dead character. Same with the Balor, one mistake and you can have a good chunk of the party eating dirt.
Of course if you have a really big blast and can use a couple of them in a turn, plus have some control effect on the side you are definitely doing your job. But ultimately, the guy who can get the thief to tear down a monster a round (or even two rounds) earlier is going to have the best time. Because every creature at epic is so dangerous, you want to remove them as fast as possible (because they can ramp up damage just as quickly!).
The Warlord is an exceptional leader because he makes important nasty monsters like those dead *the fastest*, while also ensuring the party can't take as much damage from them. For example, he also ensures that the party goes first as well, so getting caught by bursts/blasts is much more difficult (as you can spread out). Shamans can waste entire attacks, because the spirit cannot be targeted by AoE powers. The Ardent has plenty of effective bursts/blasts, plus
very deep healing reserves if he carries energizing strike into epic tier. The Bard is actually a really solid enabler and gets plenty of dominate/control effects. An epic sentinel brings an amazing amount to the table if built for summons.
The Cleric before had huge controller bursts and had the best overall individual healing. But healing does not make a leader anymore, because as many people will say - MM3 damage easily cuts your healing. So you need to do something other than heal to be an effective leader. What is that for the cleric? I don't really see them having a great amount of enabling and they don't have a great amount of control either (single target control easily goes to the bard). They don't bring the great druid controller summons to the party like the sentinel does. They don't have the ardents individual bursts/blasts or features. They can't enable like a warlord.
All of the above can heal and heal effectively. The Cleric brings more healing yes, but they aren't bringing anything else. That's a problem and if wizards felt they were overdone on the controller that
is fine. So I have no problem with them nerfing the bursts, IF they fixed many of the useless standard action utilities and gave something back leader wise. If Astral Storm was area burst 2 and gave a solid leader effect, sure, I could buy that. As it is they just nerfed the power into oblivion, while not even fixing the rubbish powers nobody took anyway.
For an example, I may have made Astral Storm give a area burst 2 within 20; allies within the burst gain resist 10-15 to all the damage keywords of this spell while within the zone. That would be very good against epic tier demons and elementals (who often have various types of elemental damage). Enemies would have gained vulnerability to the same damage types. Alternatively, I would have made it bolster allies by maybe giving a +2 bonus to attack rolls or anything like that. Basically I would have said "Okay, the burst is excessive but let's make it a GREAT leader power instead".
Now it's just a mediocre power nobody will take, while not fixing any of the actual problems the cleric has. It can't be because things are overpowered, because there is a huge gulf in effectiveness between the cleric and warlord. Yet the Warlord didn't get touched except some clarifications. It makes me wonder what on earth Wizards is thinking lately.